Fuel system and pressure switch therefor



Aug. 4, 1942. D. SAMIRAN 2,291,654

FUEL SYSTEM AND PRESSURE SWITCH THEREFOR Filed Aug. 21, 1940 2Sheets-Sheet l z- 4, 1942- D. SAMIRAN 2,291,654

FUEL SYSTEM AND PRESSURE SWITCH THEREFOR Filed Aug. 21, 1940 2Sheets-Sheet 2 Patented Aug. 4, 1942 OFFICE FUEL SYSTEM AND PRESSURESWITCH THEREFOR David Samiran, Fairfield, Ohio Original applicationMarch 13, 1939, Serial No. 261,542. Divided and this application August21, 1940, Serial No. 353,539

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 21 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

The present invention relates in general to fuel systems provided with aplurality of separate fuel sources and more particularly to a fuelsystem in which the contents of fuel containers representative of suchfuel sources are automatically connected in predetermined order to asource of fuel consumption, the present application being a division ofmy co-pending application, Serial No. 261,542 filed March 13, 1939.

It is an object of this invention to make use of fuel pressure drop ina'fuel pressure switch of novel construction induced by successive fuelexhaustions to effect automatic connection of the source of fuelconsumption with a succeeding full fuel container, the action of thefuel pressure switch being modified by changes in pressure of asupercharger when the present invention is applied to an airplane engineor the like employing a supercharger in connection with the fuelinjector or carburetor of the engine.

A further object is to provide a fuel pressure switch of suchconstruction and operation that it may be interconnected with the fuelsource selector means to accomplish a resetting of the fuel pressureswitch by the selector means when a, new fuel source has been connectedwith the source of fuel consumption by the selector means.

Still a further object is to provide a fuel pressure switch wherein thebuilding-up of fuel pressure carries the switch (in an open circuitcondition) from one position to another; the fuel selector means thencooperates with the switch to open the circuit thereof when the newsource of fuel has been completely connected with the source of fuelconsumption and subsequently when the new source of fuel becomeexhausted and the fuel pressure accordingly recedes, the fuel pressureswitch thereupon returns to position to effect closure of the circuit,the circuit controlled by the switch being in turn connected with thefuel source selector means to shift it to a new position for receivingfuel from another full container.

The foregoing mentioned objects and advantage of my invention willbecome apparent from the following description taken in connection withthe accompanying drawings, it being clearly understood that the same areby way of illustration only and are not to be taken as in any waylimiting the spirit or scope of my invention. On

the contrary the spirit or scope of my invention is to be limited onlyby the prior art and by the terms of the appended claims.

Referring now to the drawings wherein like reference charactersdesignate similar parts throughout the several views:

Figure 1 is a diagrammatic representation of a fuel system embodyin myinvention and including my novel fuel pressure switch.

Figure 2 is an enlarged sectional view through the pressure switchitself showing the parts in one position and cooperating with a cam ofthe source selector means; and

Figure 3 is a side elevation of the lower portion of Figure 2 showingthe switch in further positions which it assumes during operation.

In the present invention I seek to accomplish two objectives.

First, I am concerned with providing means whereby a source of fuelconsumption, such as an internal combustion engine fuel injector, orcarburetor, may be readily interconnected with any one of a plurality offuel containers through simple manual turning of the control handle of aselector valve.

Second, I seek to provide means for automatically turning the aforesaidselector valve from a container from which all fuel has just beenexhausted to the next fuel container in selector valve order from whichfuel has not yet been exhausted. To accomplish the second objective Iprovide a selector valve operating means including a fuel pressureswitch which is primarily responsive in two different positions topresence and substantial reduction of the pressure of the fuel beingsupplied to the fuel injector or carburetor, the switch in turnelectrically controlling the operation of the fuel selector means whichitself is of an electrically operated type.

Merely by way of illustration-I provide three fuel containers I, 2 and3. Obviously a greater or less number of containers may be providedwithout in any way departing from the spirit of my invention. The fuelcontainers I, 2 and 3 are separately connected to a like number ofinlets provided in a selector valve I by means of copper tubes or thelike 5, 6 and I respectively. A single outlet 8 from the selector valve4 is connected by a conduit 9 to a fuel strainer ID. The outlet of thefuel strainer is connected by conduits I I, I2 and I3 to an enginedriven fuel pump I4 and a manually operated wobble pump I5. The shaft ofthe pump I4 is indicated at I6 and of course is appropriately andoperatively connected with the engine (not shown).

The outlet of the fuel pump I4 is connected with a switch pressureregulator H, the construction of which is shown in my co-pendingapplication hereinbefore referred to. Fuel from the'pump l4 passesthrough the regulator I1 and then through pipes l3 and I! to anair-vapor eliminator 20 also shown in my co-pending application. The airvapor eliminator 20 and the switch pressure regulator l1 are describedin detail in my additional co-pending application Serial No. 335,646filed May 16, 1940, and Patent No. 2,275,472, dated March 10, 1942,respectively. When the wobble pump 15 is operated, fuel passes through apipe 2| and the pipe I! to the airvapor eliminator 23. The air and vaporfrom the eliminator 20 may be returned through a pipe 22 to one of thefuel containers such as 3 and the fuel under pressure from the air-vaporeliminator is conducted through a pipe 23 to a fuel injector orcarburetor (a fuel injector bein indicated at 24).

The switch pressure regulator l1 supplies fuel under pressure through acopper tube or the like 25 to the fuel pressure switch of my presentinvention indicated generally at S. The construction of the regulator I1is such that the fuel pressure in the tube 25 never exceeds apredetermined amount somewhat lower than the normal pressure of fuelsupplied by the pump l4 to the air-vapor eliminator 20 as determined bythe setting of the pressure regulator. The injector 24 includes a bypassvalve 26 set at a predetermined pressure so that fuel in excess of therequirements of the injector 24 are returned through a pipe 21 to theintake side of the pump I 4.

Returning now to the specific structure of the selector valve 4, asuitable housing is provided with the three 90 spaced inlets a, 6a and1a receiving the discharge ends of the pipes 5, 6 and 1 respectively.Within the casing of the selector valve, a truncated conical cavity isprovided which receives a cork faced tapered valve plug 23. The corkfacing is indicated at 29. The valve plug 28 is provided with a shortdriving shaft 30 protruding through a boss 3| of the valve casing. Thevalve plug is provided with an L-shaped passageway 32 having a short endprojecting through the valve plug face of smaller diameter and coaxiallylocated with respect to the shaft 30 and the outlet 8. The L-shapedpassageway 32 has a long end disposed normal to the axis of the shaft30, such that it may be successively registered with the intake bosses5a, 5a and 1a. a

In order that the selector valve 4 may be remotely controlled from acontrol panel 33, I have provided an extension shaft 34 coupled to thevalve operating shaft 30 as by a coupling sleeve 35 and suitable drivepins. A control handle 36 is fixed to the opposite end of the extensionshaft 34 and is provided with a pointer 31 to cooperate with indicia as"No. 1, No. 2, No. 3 and ofi indicating that the selector valve connectsthe fuel pumping system with any tank I, 2 or 3 or with none of them.

For effecting automatic rotation of the extension shaft 34 and therebychanging the position of the selector valve 4 without attention by theoperator, I provide the following described solenoid operated ratchetmechanism. A ratchet wheel 33 is secured to the shaft 34 and is adaptedto be rotated in one direction by a pawl 39. The pawl 33 is pivoted to acore operated plunger 40 which in turn is connected with a core 4|within a solenoid coil 42'. Whenever the solenoid coil 42 is energized,the plunger 40 and the pawl 33 are propelled in a right-hand directionfor engaging a tooth of the ratchet wheel for imparting clockwiserotation thereto through a distance of one tooth. The core 41 is springreturned as by a spring 43 so that when the coil is de-energized, thepawl 39 will be pulled backwardly and will drop behind the next tooth ofthe ratchet wheel.

From the construction of the parts just described, it will be obviousthat energization of the solenoid will cause a single tooth advancementof the ratchet wheel. It is desirable, however, that the ratchet wheelrotate in order to shift the L-shape passageway 32 from one inlet of theselector valve'4 to the next one as for instance from the inlet 5a tothe inlet 6a. To accomplish this result, I connect a toggle switch 44 inseries with the solenoid coil 42 and operate the toggle switch bylocating its operating lever 45 between a pair of projections 44 on theplunger 40. Accordingly, when the solenoid is energized, it will beadvance the ratchet wheel one tooth and in doing so will swing the lever45 of the toggle switch 44 to 011" position so that the spring 43 willreturn the pawl 33. The return of the pawl effects return of the toggleswitch 44 to "on position so that there will be another energization ofthe solenoid coil and the cycle repeated so long as current is suppliedthrough the switch 44 to the solenoid. The current, however, isautomatically and usually shut off on the quarter turn as willhereinafter appear.

Also affixed to the extension shaft 34 is a control disc 41. The disc 41has a plurality of cam lobes 41a, 41b and 41c corresponding respectivelyto the inlets 5d, 6a and 1a of the selector valve 4. The control disc 41is adapted to cooperate with the switch S as will be described after theconstruction of the switch itself has been described.

The fuel pressure responsive switch 8 is composed of many partsvariously disposed in and about a cylindrical housing 43. The housing 48has a top wall 49 and a bottom plate 50. The plate 50 is mounted ontheplate 44 as by cap screws or the like 5| with a gasket 52 interposedbetween the housing and the plate 50. A washerlike element 53 isinterposed between the gaskets and the plate 50 and has one end of thebellows 54 secured to its inner diameter. The other end of the bellowsis secured to the outer diameter of a disc 55 to which an operating stem56 is secured.

The stem 56 extends slidably through a bearing sleeve 51 in the plate53. The pressure line 25 shown diagrammatically in Figure 1 communicateswith a boss 54, which in turn is connected by a passageway 33 to acavity 63 within the ,housing 48 surrounding the bellows 54. Theinterior of the bellows constitutes a cavity 6| which is vented at 62 toatmosphere to avoid restricting the response of the bellows 54 to fuelunder pressure from the conduit 25.

Above the partition 43, a cylindrical member 63 is secured to thecylindrical housing 43 by cap screws 64 or the like with a diaphragmwasher 65 interposed between the member 53 and a gasket 66. The gasket63 seals the diaphragm washer 65 with respect to the partition 49thereby providing a sealed cavity 41 within a bellows 63. The bellows 44has one end secured to the inner diameter of the washer 55.

The fuel system shown in Figure 1 includes a 82 of an adjusting nut 83.

cooperate with the roller I 08 for holding the roller in either theposition of Figure 2 or the full line position of Figure 3' after theswitch arm I88 has been swung to either of said positions.

The contactor plates I89 and II are assembled in position on thecarriage bar 95 as by screws II2 with blocks of insulation H3 and H4 theexhaust. gases from the engine,- some of.

which may be permitted to escape through a bypass I5if there are exhaustgases in excess ofdownwardly extending sleeve 80; .The sleeve 80 isprovided witha pair of-diametrica'lly opposite slots SI which slidablyreceive apair of fingers A stop-ring 84 for the fingers 82 is providedin agroove around the sleeve 80 adjacent its lower end. The adjustingnut 83 is threaded on the lower end of an and the stem 85v together withthe parts 19 and 81 are all secured together by a lock nut 88. The stem85 is provided with a flange 89 to engage against the plate I9 for thepurpose of providing a. rigid assembly. The adjusting nut 83 is providedfor changing the tension of a spring 90 interposed between the adjustingnut 83 and a seat 9I in the partition 49.

The carriage bar 81 is connected by tie-rods 92, lock washers 93 andlock nuts 94 to a second carriage bar 95. The tie-rods 92 are slida-blein holes 98 drilled through the tubular housing 48 and through holes 91drilled through the member 63 and arranged in alignment with the holes98. To conserve space on the drawings, the central portions of thetie-rods 92 have been broken away in Figure 2 and the bosses 58 and 11shown, whereas, actually the bosses are not in the plane of thetie-rods, but are rotated a substantial number of degrees around thehousing 48 to avoid interference with the tie-rods.

The stem 58 of the bellows 54 is provided with a shoulder 98 adapted toengage a hub 99 of the carriage bar 95 to propel it downwardly againstthe bias of the spring 90. The lower cover plate is tapped as indicatedat I00 to receive a projecting stud IOI. A check nut I02 retains thestudin any desired adjusted position. Prior to installation of the studNH and the nut I02, a sheet of insulation I03 is fastened against thecover plate 50 and the vent 82 extends through both the cover plate andthe sheet of insulation.

The lower carriage bar 95 is provided with a pair of perforated ears I04carrying a pivot pin I05. A switch arm I08 is pivoted thereto and has aslidably mounted plunger I01 formed of suitable insulating material. Theplunger I01 carries a metallic roller I08 adapted at times to bridgecontact plates I09 and H0 as shown in Figure 2. The plunger I 01 and theroller I08 are urged toward the contact plates by a spring III, theplunger I01 being guided against rotation by slots and pin connectionI08a--I06b. The contact plate I09 has a knife or V-edge to to properlyinsulate them from each other and from the other metallic parts of thestructure shown in Figure 2. The switch arm I08 has a cam lobe us tocooperate with any one of the cam lobes 41a, 41b, or 41c of the controldisc 41, as will hereinafter appear.

The tension of the spring 90 may be adjusted by first loosening the locknut 88 and then turning the adjusting stem by means of a screwdriver ina slot II8 ofithe stem. Turning of the-stem causes the spring adjustingnut 83 to be lowered or raised to effect increase or decrease of thespring tension as-desired. Thereafter, the nut 88 may be retightened toretain the adjustment and to compress the gasket 86. This adjustmentassures awide range of varying spring compressions tending to maintainthe spring carriage 8192--95 in araised-position. The projecting studIOI may be' adjusted to different positions as desired by inserting apin through an opening Ill thereof and turning the stud after the checknut I02 has been loosened. It is preferred to adjust the stud IOI toaposition where the further'upward displacement of the carriage8I'-92-95 by the spring 90, after the roller I08 is brought intobridging contact with contacts I09 and H0, will cause the arm I06 toagain contact the stud I M to thereby maintain the roller I08 inengagement with the contact IIO with a substantial force.

The upper portion of the fuel pressure switch S is provided with a dustcover Illa, which is vented as at II8 to atmosphere to preventcompression ofair within the dust cover surrounding the bellows .68 andinterfering with its action. In the event that the switch S is used withan unsupercharged engine, the pipe connection I6 with the boss 11 isdispensed with and the .boss vented to atmosphere, thereby venting theinterior of the bellows 88 to atmosphere.

1 Referring again to the diagrammatic'showing in Figure 1, theelectrical control circuit for the selector -valve operating ratchetwheel 38 controlled by the switch S includes a source of electriccurrent such as a battery II9. An ignition switch for the engine isindicated at I20. The switch I20 is connected by a wire I2I to thenegative side of the battery H9 and a wire I22 extends to the ignitionsystem of the engine in the usual manner. A terminal panel I23 isprovided on which is mounted a negative terminal I24. a positiveterminal I25, and a control terminal I26. The negative terminal I 24 isconnected with the ignition switch I20 by a wire I21 to that current issupplied to the terminal panel I23 only when the ignition system is inoperation. By a wiring arrangement of this character, the automaticoperating mechanism for the selector valve is rendered inoperative anytime the engine is not in operation.

The positive terminal of the battery I I9 is connected by a wire I28with the positive terminal I25 of the terminal panel I23. Current issupplied from the terminal I25 through wires I29 and I30 to the switch Sand to an indicator light I3i respectively. The wire I29 is connectedwith the contact plate I09 of the switch S while the contact plate IIOthereof is connected by a wire I 32 with the control terminal I26. It isaccordingly obvious that whenever the roller I09 bridges the contactsI09 and I I current will be supplied from the positive side of thebattery II9 through I28, I25, I29, I09, I08, H0 and I32 to the terminalI26. From the terminal I26 the current divides so that part goes througha wire I33 to a test switch I34 of the indicator light I3I and to theelectric bulb I35 of the indicator light. The current to the bulb thenreturns through a wire I36 and through I24, I21, I20 and III to thenegative side of the battery. Thus closure of the switch S automaticallyenergizes the indicator I35.

Any time the operator desires to test the indicator light, a push rodI31 may be pushed inwardly for closing the test switch I34, which isconnected directly across the positive and negative terminals I25 andI24 of the panel I23 with the bulb I35 in series therewith.

Closure of the switch S also causes the rest of the current from theterminal I26 to flow through a wire I38 to a relay coil I39, returningby way of a wire I40 to the negative terminal I34. Energization of therelay coil I39 causes it to attract an armature I of the relay(indicated generally at R) thus closing the contacts I42 of the relay.Current from the positive terminal I24 is supplied through a wire I43 tothe contacts 2 from which it flows through a wire I44 to a selectorswitch I45 mounted on the panel 33. The current then flows through awire I46 to the toggle switch 44 and a wire I41 to the solenoid coil 42,returning by way of a wire I48 to the negative terminal I24 on theterminal panel I23.

From the explanation of the parts just referred to, it is obvious thatclosure of the switch S, in addition to operating the indicator lightI3I operates the solenoid 42 through the medium of the relay R whereuponthe solenoid in conjunction with the toggle switch 44 produces step bystep rotation of the ratchet wheel 38 as already described. Rotation ofthe ratchet wheel also rotates the control disc 41 with its cams 41a,41b and 410, which so cooperate with the switch S that they open theswitch at the completion of a quarter turn of the selector valve 4.

In order to understand just how the control disc cooperates with theswitch S I will now refer to Figure 2. Due to a drop in pressure in theconduit 25 and a consequent drop in pressure in the cavity 60surrounding the bellows 54, the bellows in Figure 2 has been expanded bythe spring 90. The drop in pressure in the conduit 25 is a result of thefuel tank I becoming emptied and thereby the pump I 4 running out offuel. The tanks 2 and 3, however, are full as indicated by the liquidlevel lines 2a and 3a respectively.

In Figure 2 the switch carriage, consisting of the carriage bars 81 and95 and the tie-rods 92, is in raised position which causes theprojecting stud IN to be engaged by the switch arm I06 and the switcharm therefore to be swung downwardly with relation to the carriage bar95, Accordingly, the roller I08 has passed across the knife edge of thecontact I09 and bridged the contacts I09 and H0. The circuit is nowclosed through the switch S thereby effecting energization ofJ-theindicator bulb I35 and the relay R. The solenoid 42', under control ofthe relay, is accordingly energized and the rotation of the ratchetwheel 38 is just commencing.

While the cam lobe 41a is rotating a quarter turn clockwise, the cam 41bis coming up to position of alignment with the switch arm cam lobe II asshown by dotted lines in Figure 3. When the L-shaped passageway 01' theselector valve 4 begins to register with the inlet 6a of the selectorvalve, the pump I4 will start to pump fuel to the fuel injector 24,Accordingly, the pressure will be built up in the switch pressureregulator I1 and in the conduit 25 leading to the cavity 60 of theswitch S.

This will result in the pressure of the fuel forcing the bellows 54 tocollapse against the action of the spring 90, thereby moving'the switchcarriage from the position of Figure 2 to the position of Figure 3 withthe switch arm I06 in dotted position. Such movement downwardly of thecarriage will occur prior to registry of the cam lobe 41b with the camlobe I I5. When the quarter turn is completed, the cam lobe 41b willengage the cam lobe H5 and swing the switch arm: I06 upwardly to thefull line position thus breaking the circuit at the switch S and therebydeenergizing the solenoid 42 and stopping the ratchet wheel at theproper position with the L-shape passageway of the selector valve inexact registry with theinlet 6a.

If it so happens that the fuel tank 2 is empty, then, of course, thepressure will not be built up in the pipe 25 to move the switch carriagefrom the position in Figure 2 to the position of Figure 3 with theresult that the switch S' will remain closed in the position of Figure 2to permit the cam lobe 41b to pass without opening the switch.Subsequently the cam lobe 410 will open the switch when the L-shapedpassageway is in registry with the intake 1a of the tank 3 providingthere is fuel in the tank 3. Thus I am assured of automatic changing ofthe position of the selector valve from an empty tank to a tank havingfuel in selector valve order.

Due to the ratchet and pawl mechanism 3839, the selector valve can bemanually moved clockwise by the control lever 36 to connect with anydesired tank. If at any time the operator wishes to render the automaticselector valve operating mechanism inoperative, he can do so by openingthe selector switch I45. The spring 'of the switch S may be set at thedesired value for proper closing of the switch S or downward shifting ofthe switch carriage as in Figure3 in accordance with the desired low andhigh fuel pressures effective in the cavity 60.

Where an aircraft in which my system is installed is equipped with anengine having a supercharger that controls the supply of air to theintake of the engine, the pressure required to deliver fuel to theinjector remains substantially constant due to the action of thepressure relief valve 26 of the injector as the aircraft continues togain altitude. Air pressure against the inside of the bellows 54 howeversteadily decreases. It naturally follows that the. aforesaid decrease inair pressure tends to collapse the bellows 54. Should only the spring 90resist the aforesaid collapse of the bellows, premature downwardmovement of the switch carriage would result.

To prevent such premature movement, the cavity 61 within the upperbellows 68 is directly fiuid connected through the pipe 16 with the induction system of the supercharged engine as by connection into thepressure supply pipe H of the supercharger 69. This effects completecompensation for the fuel pressure increase above mentioned. Suchcompensation is a result of the supercharger maintaining a substantiallyconstant pressure on the air supplied to the engine. The purpose of asupercharger is to maintain such constant pressure (for instance, sealevel pressure) regardless of the altitude to which the airplaneascends. Accordingly by making the connection at 16, the constant airpressure supplied by the supercharger will also maintain a substantiallyconstant pressureinside the bellows 68. Outside of the bellows 68-ambient air pressure decreases as the altitude increases thereby tendingto expand the bellows 68. This results in a tendency to produce upwardmovement of the switch carriage whereas the reduced ambient air pressureacting inside the bellows 54 as above pointed out tends to producedownward-movement thereof. Accordingly, constant fuel pressure withinthe chamber 60 surrounding the bellows 54 and constant superchargerpressure within the cavity 6'! inside the bellows 68 balance each otherto prevent movement of the switch carriage as long as fuel is suppliedto the fuel pump and the ambient air pressure tending to collapse thebellows 54 and expand the bellows 68 cause a further balance resultingin the desired compensation. The result is that the movement of theswitch carriage is accurately in response to changes in the fuelpressure to give the desired operation to the switch which in order tooperate the selector valve properly must respond to fuel failure asreflected in a drop of fuel pressure when the pump runs out of fuel.

Having described a fuel system in which my pressure responsive switch isused together with the operation thereof, it is believed obvious how theselector valve 4 is automatically changed from one position to anotherin response to the emptying of any of the fuel containers I, 2 or 3under control of the switch S, the switch in turn being responsive to apredetermined drop in fuel pressure occasioned by emptying of a fuelcontainer (and its response being modified by connection with asupercharger in the event that the engine is so equipped). Thesupercharger connection compensatesfor a gain in altitude of theaircraft in which the system is installed. ;Where there is nosupercharger, then the interior cavity 61 of the bellows 68 is vented toatmosphere so that the bellows 68 is inefiective to modify the action ofthe bellows 54.

My invention has been described in the foregoing specification andillustrated in the drawings more or less precisely as to details. It isto be. understood, however, that changes may be made in the arrangementand proportions of parts and equivalents may be substituted withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What I claim as my invention and desire to secure by Letters Patent ofthe United States is:

1. A pressure responsive switch'for use in a fuel dispensing systemincluding a selector valve, means for operating said switch inconjunction with said selector valve comprising a bellows with anexternally projecting stem, 2. support piloting said projecting stem andsubstantially closing the open bellows end, and contactor means carriedby said support and adapted to be closed by said projecting stem uponpredetermined bellows expansion effecting movement of said support, saidswitch cooperating with said selector valve to be opened thereby onlywhen said support is in a predetermined position.

2. A pressure responsive switch for use in a fuel dispensing systemincluding a selector valve, means for operating said switch inconjunction with said selector valve comprising a bellows with anexternally projecting stem, 3. support piloting said projecting stem andclosing the bellows end,

a single fluid inlet-outlet connected with said bellows, and contactormeans carried by said support, adapted to be closed by said projectingstein upon predetermined bellows expansion, and adapted to be opened bysaid selector valve assuming a selector position at a time when saidsupport is in the position it assumes as a result of bellowscontraction.

3. A pressure responsive switch for use in a fuel dispensing systemincluding a selector valve, means for operating said switch inconjunction with said selector valve comprising a bellows with anexternally projecting stem, 9. support substantially closing the openend of said bellows, a spring positioned to resist collapse of saidbellows, and contactor means carried by said support and so tensionedagainst said projecting stem as to close upon predetermined bellowsexpansion efifectmg movement of said support, said switch cooperatingwith said selector valve to be opened thereby only when said supportisin a predetermined position.

4. A pressure responsive switch for use in .a fuel dispensing systemhaving a selector valve, said switch including a bellows with anexternally projecting stem, a support providing the open bellows endwith a single fluid inlet-outlet, a spring positioned to resist collapseof said bellows, and contactor means carried by said sup port and sotensioned against said projecting stem as to close upon predeterminedbellows movement due to pressure drop and to be opened by said selectorvalve due to pressure rise and assumption of a selector position by saidselector valve.

5. A pressure responsive switch for use in a fuel dispensing systemhaving'a selector valve and an electrically operated means for changingthe position thereof, said pressure responsive switch comprising aswitch carriage, pressure responsive means connected with the fueldispensing system so as to be responsive to pressure or absence ofpressure therein and operabl to move said switch carriage in onedirection upon decrease of pressure and in an opposite direction uponincrease of pressure, a switch carried by said switch carriage andoperable to closed position by engagement with a stationary stud whensaid switch carriage moves in said first mentioned direction as a resultof fuel pressure decrease, said switch being operable to remain closedand to be moved bodily by said switch carriage when said carriage movesin said opposite direction as a result of fuel pressure increase, saidswitch being opened by said means for changing the position of saidselector valve when said means assumes a new selector valve position andsaid switch being connected in circuit with said means to energize anddeenergize the same in response to closing and opening of said switch.

6. A pressure responsive switch for use in a fuel dispensing systemhaving a'selector valve and solenoid operated ratchet means for changingthe position of said selector valve, said solenoid operated ratchetmeans including a toggle switch in circuit with the solenoid to causerepeated energizations and deenergizations of the solenoid during thetime current is supplied thereto, said pressureresponsive switchcomprising a switch carriage, pressure responsive means connected withthe fuel dispensing system so as to be responsive to absence of pressureor presence of pressure therein and operable to move said switchcarriage respectively in one direction or in the opposite direction as aresult thereof, a

-switch carried by said switch carriage and opermoves in said firstmentioned direction as a result of absence of fuel pressure; said switchbeing operable to remain closed and to be moved bodily by said switchcarriage when it moves in said second mentioned direction as a result ofpresence of fuel pressure, said switch being opened by said solenoidratchet operated means ofsaid selector valve when it assumes a newselector valve position and being connected in circuit with saidsolenoid and toggle switch.

7. A pressure responsive switch for use in a fuel supply system for anengine having a supercharger, said system having a selector valve andelectrically operated means for changing the position of the selectorvalve, said switch comprising a switch carriage, pressure responsivemeans connected with the fuel supply system so asto be responsive toincrease and decrease of pressure therein, said pressure responsivemeans being in communication with said supercharger for modification ofthe pressure responsive means in. response to variations in pressureproduced by the supercharger, said pressure responsive means beingoperable to move said switch carriage in one direction upon decrease offuel pressure and in an opposite direction upon increase of fuelpressure, a control-switch for said electrically operated means, carriedby said switch carriage and operable to closed position when said switchcarriage moves in said first mentioned direction, said control switchbeing operable to remain closed and to be moved bodily by said switchcarriage when said carriage moves in said second mentioned direction,said control switch being opened by said electrically operated meanswhen said means assumes a new selector valve position and said controlswitch effecting control of the circuit of said'electrically operatedmeans.

8. A pressure responsive switch for use in a fuel dispensing systemhaving a selector valve, a shaft for rotating the selector valve andelectrically operated means for rotating said shaft, said pressureresponsive switch comprising a switch carriage, pressure responsivemeans connected with the fuel dispensing system for response to absenceor presence of pressure therein, said pressure responsive means beingoperable to move said switch carriage in one direction upon decrease ofpressure and in the opposite direction upon increase of pressure, aswitch carried by said switch carriage and operable to closed positionwhen said switch carriage moves in said first mentioned direction,operable to remain closed and to be moved bodily by said switch carriagewhen it moves in said second mentioned direction, and a cam on saidshaft for opening said switch when the cam assumes a positioncorresponding to a new selector valve position, said switch beingconnected in circuit with saidv electrically operated means to energizeit by decrease of pressure in said pressure responsive means to apredetermined valve and deenergize it in response to said cam providingsaid pressure responsive means has in the meantime responded to anincrease in pressure suflicient to move said switch carriage to aposition where the closed switch thereof may be engaged by said cam.

' 9. 'A pressure responsive switch for use in a fuel dispensing systemhaving a selector valve, a shaft for rotating the selector valve andelectrically operated means for rotating said shaft, said switchcomprising a switch carriage, pressure responsive means connected withthe fuel dispensing system for response to changes of pressure therein,a control switch carried by said switch carriage andoperable to closedposition' when said switch carriage moves in one direction, operable toremain closed and 'to be moved bodily by said switch carriage when itmoves in the opposite directionand means on said shaft for opening saidswitch'when saidlast means assumes a position corresponding to a newselector valve position, said switch being connected in circuit withsaid electrically operated means in energize it by decrease of pressurein said pressure ,responsive means as a result of fuel failure and todeenergize it in response to said means on said shaft providing saidpressure responsive means has in the meantime responded'to an increasein pressure sufilcient tomove said switch carriage to a position wherethe closed switch thereof may be engaged by said means on said shaft;

10. A pressure responsive controller for use in a fuel dispensing systemhaving a selector valve, a shaft for rotating the selector valve andmeans for rotating said shaft, said controller comprising a movablemember,- pressure responsive means operatively connected therewith andfluid connected with the fuel dispensing system for response to changesof pressure therein, a control device carried by said movable member andoperable to operative position when said'movable member moves in onedirection, operable to remain in operative position and to-be movedbodily by said movable member when it moves in an opposite direction,and means on said shaft for rendering said control device inoperativewhen the last means assumes a position corresponding to a new selectorvalve position, said control device being operatively connected withsaid means for rotating said shaft-to render it operative by decrease ofpressure in said pressure responsive means to a' predetermined value,said means for rotating said shaft being rendered inoperative inresponse to said means on said shaft, providing said pressure responsivemeans has-in the meantime responded to an increase in fuel pressuresufficient to'move said movable member to a position where the operativecontrol device tlfiereof may be engaged by said means on said s aft.

11. A pressure responsive control device for use in a fuel dispensingsystem having a'selector valve and means for changing the positionthereof, said pressure responsive device comprising a carriage, pressureresponsive means connected with the fuel-dispensing system so as to beresponsive to pressure or absence of pressure therein and operable tomove said carriage in one direction uporidecrease of pressure and manopposite direction'upon increase of pressure in said fuel system/acontroller for'said means carried by said carriage and operable tooperative position when said carriage is moved'in said first mentioneddirection as a result of fuel pressure decrease; saidcontrollerremaining operative and being moved bodily by said carriage when saidcarriage moves in said oppositedirection as a result of fuel pressureincrease, said controller being rendered inoperative by said means whenit causes said selector valve to assume a new selector valve position. v

12. A pressure responsive switch for use in a fuel supply system for anengine having a super-.

pressure responsive means connected with the fuel supply system so as tobe responsive to pressure therein, said pressure responsive meansbeingin communication with said 1 supercharger fonmodificationof theposition of the pressure responsivemeans .in response to'variation's inpressure produced by thesupercharger, said pressure responsivemeansbeing operatively'connected with said switchrcarriage, a switchcarried by saidswitch carriage andoperable' to closed'position byengagement with an abutment sure responsive switch comprising a switchcarfirst mentioned direction, said switch being openable to remain insaid one position and to be movedbodily by said switch carriage when thewhen said switchcarriage moves in one direction as are'sult of fuelpressure decrease and superv charger pressure increase, said switchbeing operable to remain closed and to be moved bodily by-said switchcarriage when said carriageamoves in'the'opposite direction as a resultof fuel pressure increase and supercharger pressure idesv crease, saidswitch being. opened'by: said-means for changing-the position of saidselector valve when'said means assumes-a newselector valve position andsaid switch being operatively con- 1 'nected to 'the circuit of saidmeans to energize the samein response to closing of said switch.

'13.-.A pressureresponsive switch for use in a fuel'dispensing systemhaving a selector valve and solenoidroperated ratchet means .forchangin'gthe position of said selector-valve, acontrol switch for thecircuit of saidsolenoid, a switch carriage, pressure responsive meansconnected with thepfuel dispensing system so as to be responsive to thepressure of fuel therein and operable to move said switch carriage inone direction or an opposite direction as a result of fuel pressurechanges, said control switch being carried by said switch carriage, astationary abutment, said control switch being operable to closedposition by engagement with said stationary abutment when said switchcarriage moves in said first mentioned direction, said control switchbeing operable to remain closed and to be moved bodily by said switchcarriage when it moves in said second mentioned direction, said switchbeing opened bysaidsolenoid ratchet operated means when it assumes a newselector valve position.

14. A pressure responsive switch for use in a fuel supply system for anengine having a supercharger, said system having a selector valve andelectrically operated means for changing the position of the selectorvalve, said switch comprising a switch carriage, pressure responsivemeans for operating said switch carriage and connected with the fuelsupply system so as to be responsive to changes of pressure therein,said pressure responsive means being in communication withsaidsupercharger for modification of the position of said switch carriage inresponse to variations in pressure produced by the supercharger, acontrol switch carried-by said switch carriage, a stationary abutmentthereadjacent, said control switch being operable to closed position byengagement with said stationary abutment when said switch carriage movesin one direction, operable to remain closed and to be moved bodily bysaid switch carriage when said carriage moves in the opposite direction,and

opened by said means for changing the position of said selector valvewhen said means assumes a new selector valve position and said switcheffecting control of the circuit of said means.

15. A pressure responsive switch for use in a fuel dispensing systemhaving a selector valve and solenoid operated ratchet means forchangcarriage moves in said second mentioned direction. said switchbeing moved to its other position by said solenoid ratchet operatedmeans of said'selector valve when it assumes a new selec-, tor valveposition and being operable to energize the circuit of said. solenoidwhen in saidone position: and to deenergize it when in said otherposition. I I .a Y

7 l6. A-pressure responsive switch 'for controlling electricallvoperatedmeansfor changing the, position of a selector valve of a fuel dispensingsystem, said pressureresponsive switch comprising a movable member,pressureresponsive means responsive to pressure of said fuel dispensingsystem andoperable to move said movable member in one direction upondecrease of fuel pressure ing the position of said selector valve, saidpresand in an opposite direction upon increaseof fuel pressure, a switchcarried bysaid movable member and connected in circuit with saidelectricallyoperated means to energize the samein response to closing ofsaid switch, said switch being operable to closed position by movementof said movable member in said first mentioned direction as a result offuel pressure decrease, said switch being operable to remain closed uponbodily movement with said movable member when it moves in said oppositedirection as a result of fuel pressure increase, said switch beingopened by said electrically operated means when it assumes a newselector valve position.

17. A pressure responsive switch for use in a fuel dispensing systemhaving a selector valve, said switch comprising a bellows chamberresponsive to fuel pressure, a second bellows chamber, a movable switchcarriage, the bellows of said chambers being operatively connectedtherewith for moving it in one direction by increase of pressure in thefirst bellows chamber and decrease of pressure in the second one and formoving it in the opposite direction by deoperable with said selectorvalve to be changed to said initial position thereby when said valveassumes a position of registry.

18. A pressure responsive switch for use with an engine having asupercharger and a fuel dis pensing system having a selector valvecompris- I ing a bellows chamber responsive to fuel pressure, a secondbellows chamber responsive to supercharger pressure, a movable switchcarriage, the bellows of said chambers being operatively connectedtherewithfor moving it in opposite directions by increase and decreaseof pressure in said bellows chambers, a switch adapted to be carriedbodily by said switch carriage, an abutment to engage said switch andmove it to direction, said carriage when moving in the pposite directioncarrying said switch with it without moving the switch to open positionand the switch being cooperable with a selector valve of the fueldispensing system to be opened thereby in a predetermined position ofsaid selector valve. 19. In a pressure responsive switch for use in afuel dispensing system having a fuel tank selector means, a bellowschamber responsive to fuel pressure, a movable switch carriage, thebellows of said chamber being operatively connected therewith to movesaid carriage in one direction by increase of pressure in said bellowschamber and to move it in the opposite direction by decrease of pressurein said bellows chamber, a switch adapted to be carried bodily by saidswitch carriage, an I abutment to engage said switch and change theposition thereof when the carriage moves in one direction, said car--riage when moving in the opposite direction being ineffectual to changesaid switch to its initial position and the switch being cooperable withsaid fuel tank selector means to be changed to said initial positionthereby.

- 20. In a pressure responsive switch for use in a fuel dispensingsystem of an engine having a supercharger, a bellows chamber responsiveto fuel pressure, a movable switch carriage, the

closed position when the carriage moves in one bellows of said chamberbeing operatively connected therewith to move said carriage in, one,direction by increase of pressure in said bellows chamber and to move itin the opposite direction by decrease of pressure in said bellowschamber, a switch adapted to be carried bodily by said switch carriage,an abutment to engage said switch and change the position thereof whenthe carriage moves in one direction, said carriage when moving in theopposite direction being ineffectual to change said switch to itsinitial position and the switch being cooperable with a fuel tankselector means of the fuel dispensing systemto be changed to saidinitial position thereby, and means responsive to supercharger pressurefor modifying the response of said switch carriage to said fuel pressurebellows.

21. A fuel pressure responsive switch for use in a fuel dispensingsystem having selector means said switch being provided with contactorelement mounted upon a carriage movable with respect to its body portionsuch that each occurrence of predetermined fuel pressure dropautomatically locks said contactor element in closed circuit positionand that each subsequent pressure rise advances said locked contactorelement into a prearranged position from which it may be disengaged bysaid selector means.

- DAVID SAMIRAN,

